1. Field of the Invention
The present invention relates to a water-based ink set for ink-jet recording composed of a plurality of inks.
2. Description of the Related Art
When a color image is expressed by an ink-jet recording method, a three-color ink set has been generally used, composed of a yellow ink (Y), a magenta ink (M) and a cyan ink (C). Moreover, a four-color ink set has also been used in which a black ink (K) is further added to the standard three-color ink set. When a color image is formed, it is desirable that a wide range of natural colors be expressed in the image. In order to achieve this with the above color ink sets, hue (or color such as red or blue) is controlled by changing the formation ratio of dots for each of the yellow, magenta and cyan inks discharged from a head. In addition, lightness (or brightness) is controlled by changing the formation density of dots for each of the inks.
Recently, additional inks have been used in addition to the abovementioned four color inks (Y, M, C and K) to form an ink set composed of five to seven inks. This has been done to obtain improved image reproducibility and improved color reproducibility over a wide range of colors. These additional inks include a yellow ink having a low color density (a light yellow ink), a magenta ink having a low color density (a light magenta ink) and a cyan ink having a low color density (a light cyan ink). Further, another method is proposed in which at least one of a blue ink (B), a violet ink (V), a red ink (R), an orange ink (O) and a green ink (G) is employed in addition to the above four color inks (Y, M, C and K) (see Japanese Patent Application Laid-Open No. 2000-248217).
However, even with the above improvements, the desired chromaticity and saturation are not always obtained in an ink-jet recording color image. This is the case when the light yellow, light magenta or light cyan ink having a low color density is added to the conventional four color inks (Y, M, C and K). This is also the case when the additional inks including at least one of the blue ink (B), the violet ink (V), the red ink (R), the orange ink (O) and the green ink (G) are added to the conventional four color inks (Y, M, C and K).